Objective To investigate the effect of nicotinamide mononucleotide (NMN) on insulin secretion and gene expressions of pancreatic and duodenal homeobox 1 ( PDX-1 ) and forkhead box-containing protein O-1 ( FoxO1 ),which were important transcription factors for insulin secretion.Methods Insulin secretion level in RIN-m5f cells was detected by rat insulin ELISA detection kit.The mRNA expression levels of PDX-1 and FoxO1 in RIN-m5f cells were analyzed by real-time PCR.The protein expression of PDX-1 was measured by Western blot.Results Insulin secretion levels in RIN-m5f cells treated with repaglinide ( 10 nmol/L) plus NMN ( 100 μnol/L) was significantly higher than those in the blank control,the DMSO control group,and the NMN (50μmol/L) treated group (P ＜0.05 ).The mRNA expression levels of PDX-1 in RIN-m5f cells treated with NMN ( 10,50 and 100 μmol/L) for 36 h were significantly higher than those in the control group (P ＜0.05,P ＜ 0.01,and P ＜ 0.001,respectively).There was marked differences in the mRNA expression levels of PDX-1 among different concentrations of NMN (P ＜0.001 ),but no significant differences in the mRNA expression level of FoxO1 ( P ＞ 0.05).No significant difference was found in the protein expression levels of PDX-1 in RIN-m5f cells treated by NMN (50,100,and 200 μmol/L) for 36 or 48 h compared with the control group (P ＞ 0.05).Conclusion NMN can stimulate insulin secretion and upregulate the mRNA expression of PDX-1 in RIN-m5f cells.

PURPOSE: Pulmonary Kv channels are thought to play a crucial role in the regulation of cell proliferation and apoptosis. Previous studies have shown that fluoxetine upregulated the expression of Kv1.5 and prevented pulmonary arterial hypertension in monocrotaline-induced or hypoxia-induced rats and mice. The current study was designed to test how fluoxetine regulates Kv1.5 channels, subsequently promoting apoptosis in human PASMCs cultured in vitro. MATERIALS AND METHODS: Human PASMCs were incubated with low-serum DMEM, ET-1, and fluoxetine with and without ET-1 separately for 72 h. Then the proliferation, apoptosis, and expression of TRPC1 and Kv1.5 were detected. RESULTS: In the ET-1 induced group, the upregulation of TRPC1 and down regulation of Kv1.5 enhanced proliferation and anti-apoptosis, which was reversed when treated with fluoxetine. The decreased expression of TRPC1 increased the expression of Kv1.5, subsequently inhibiting proliferation while promoting apoptosis. CONCLUSION: The results from the present study suggested that fluoxetine protects against big endothelin-1 induced anti-apoptosis and rescues Kv1.5 channels in human pulmonary arterial smooth muscle cells, potentially by decreasing intracellular concentrations of Ca2+.
Apoptosis/drug effects/genetics ; Blotting, Western ; Cell Proliferation/drug effects ; Cells, Cultured ; Endothelin-1/*pharmacology ; Flow Cytometry ; Fluoxetine/*pharmacology ; Humans ; Kv1.5 Potassium Channel/genetics/*metabolism ; Muscle, Smooth, Vascular/*cytology/drug effects ; Pulmonary Artery/*cytology ; Reverse Transcriptase Polymerase Chain Reaction